The present invention relates to apparatus for manipulating discrete particles of fibrous material, such as shredded tobacco leaves or fibrous (textile) filter material (e.g., acetate fibers) which can be converted into fillers of filter rod sections for use in filter cigarettes and analogous rod-shaped articles of the tobacco processing industry. More particularly, the invention relates to improvements in apparatus for influencing particles of fibrous material during travel through a duct and during subsequent transport to a stream forming station, e.g., to a stream forming station in a cigarette maker wherein particles of tobacco and a wrapper of cigarette paper or the like are converted into plain cigarettes of unit length or multiple unit length.
It is already known to admit particles of tobacco leaves which are stored in the magazine of the distributor in a cigarette maker into an upright duct for controlled removal of particles from the duct and for further transport to the stream forming station of the cigarette maker. As a rule, the duct has two relatively large (wide) walls which flank the front and rear sides of the passage for gravitational descent of tobacco particles in the duct and two relatively narrow additional walls or end walls which alternate with the front and rear walls and define with the front and rear walls a passage having a substantially rectangular outline with two long sides and two much shorter sides. It is also known to impart oscillatory movements to at least one of the front and rear walls in order to promote the descent of tobacco particles toward the outlet of the passage in the duct. The duct is located between the aforementioned magazine and at a level above a carded drum which removes the particles at the outlet of the passage and transports the removed material into the range of a rapidly rotating picker roller for conversion into a layer containing randomly distributed heavier particles (such as fragments of tobacco ribs) and lighter particles (predominantly or exclusively fragments of tobacco leaf laminae).
Heretofore known ducts which are used for the above outlined purpose in the distributors of cigarette makers are not entirely satisfactory because they cannot ensure the delivery of particles into the range of the carding on the drum-shaped conveyor at a relatively constant rate such as is most conducive to the formation of a homogeneous layer of separated particulate material and to conversion of the layer into a homogeneous tobacco stream which is ready for wrapping into cigarette paper or the like. It is particularly important to ensure that the material is uniformly distributed in the lower portion of the duct, i.e., in the region where the particles are engaged and entrained by the carding of the aforementioned drum-shaped conveyor. If the carding of the conveyor is not uniformly filled with particles of removed tobacco, the picker roller cannot convert the removed particles into a homogeneous layer and this affects the quality of the tobacco stream which is thereupon trimmed and wrapped to constitute the filler of a continuous wrapped tobacco rod.
British Pat. No. 329,256 discloses an apparatus wherein the front and rear walls of the tobacco duct in the distributor of a cigarette maker are agitated up and down (i.e., in the direction of gravitational descent of confined particles and/or in directions toward and away from each other. Such agitation of the front and rear walls fails to ensure adequate filling of the lower portion of the duct above the removing conveyor.
U.S. Pat. No. 2,113,544 discloses a modification of the duct which is disclosed in the aforementioned British patent. The front and rear walls of the duct which is disclosed in the United States patent are caused to perform movements in a manner as disclosed in the British reference but the movements of one of these walls are superimposed upon the movements of the other wall. This proposal also failed to gain acceptance in the relevant industry because it cannot ensure adequate filling of the duct in the region of the outlet.
Published British patent application No. 2 111 370 discloses a relatively small strip-shaped member which is disposed at a level below and in the space between the lower end portions of the stationary front and rear walls of the duct. The strip-shaped member is reciprocated in the axial direction of the carded drum-shaped conveyor therebelow and is intended to uniformize the distribution of removed tobacco particles in the carding of the conveyor. Reference may also be had to commonly owned U.S. Pat. Nos. 3,996,943, 3,996,944 and 4,011,966. These proposals also failed to ensure a highly satisfactory filling of the lower portion of the duct. On the other hand, and in view of the ever increasing output of cigarette makers, the formation of a homogeneous tobacco stream for conversion into the fillers of plain cigarettes is even more desirable than before because very little time is left for homogenization once the particles reach the stream forming station.